Scheme of LED screen functioning
How large LED screens work?
LED screen is an active imaging device with LED light diodes (Light Emitting Diode) set in a matrix covering the whole screen.
LED screen works on the base of additive color addition when each point of the screen in full color is composed of three LED diodes – red, green and blue. When watching a large screen from a distance, the three colors merge and the viewer perceives them as one point. The bigger the pitch between the diodes, the further is the minimum viewing distance.
LED is put inside the screen with shades. The shades are stumps creating a shield above the LED and protect it from sunshine and mechanical damage. Black color of the screen background ensures optimum conditions for maximum usage of the color scale and light intensity. With different light intensity we can achieve displaying more than 68 billion colors!
Image data are processed by a computer via application which assigns light intensity to each LED diode. This information is sent to the processor of the screen itself. The frequency is 600 Hz – 600 times in a minute. High refresh rate ensures that the image of the screen is not flashing, which is necessary when displaying TV sport matches or concerts.
Construction parts of large LED screens
Cluster is the smallest construction item of LED screens. It is a water-proof and dust-proof segment sized 12x12x2.5cm which contains LED diodes set into a matrix and a cover made from resilient plastic. The cluster has a double connector with basic block which eliminates losing data for LED. Damaged cluster can be replaced easily with the screen on.
The basic block is the basic functioning item of large LED screens. It is composed of a motherboard with operating electronics, primary and back-up power supply and hard metal cover. On its front side there are 16 clusters (4x4). It is possible to set up a LED screen of various sizes and shapes from these blocks – the only limit is the size of the basic block – 48x48cm.
Supporting structure connects the basic block into one mechanically resistant device. It is possible to choose such a construction which is suitable for permanent installations, such as on the façade of houses or a construction which can be dismantled and set up as needed (modules of 1x1m can be combined to an arbitrary shape.
Data cable ensures communication between the operating device and the LED screen. Classic metallic network cable or optic cables for remote operation (up to kilometers) are used.
The operating device processes image information from various inputs via application ViewLab and then sends them to the electronics of the screen. The function of the operating device can be carried out by any standard PC with S-video and composite video cards, digital and analogue televisions, satellite broadcast etc. ViewLab enables to combine video signal from cameras with graphics and texts, commercial messages, information blocks including online broadcasting from the Internet of data from SMS voting.